Rotating fixture-mold for fabricating printing drums

ABSTRACT

A rotating fixture-mold for locating and holding type bearing print members in a spatical relationship to each other and to the axis of rotation of the fixture mold. The type bearing print members when molded together form a drum structure which may be used as a printing drum or as an intermediate mold.

United States Patent Hepner [4 Apr. 11, 1972 [54] ROTATING FIXTURE-MOLDFOR F ABRICATING PRINTING DRUMS f r n es Ci ed [72] Inventor: NealHepner, Birmingham, Mich. UNITED STATES PATENTS [73] Assignee: BurroughsCorporation, Detroit, Mich. 2,023,040 12/1935 Adam, Jr. 164/298 X3,214,506 10 1965 Corbin, Jr ....l8/26 R UX 1 Flledr 13, 1969 3,505,4374/1970 Eichmann et a1 ..l8/26 RR 21 A l. N 806 829 1 pp 0 PrimaryExaminer-J. Spencer Overholser Related us. A li ati Data AssistantExaminer-David S. Safran Attorne Paul W. Fish and Edwin W. Uren [62]Division of Ser. No. 690,041, Nov. 15, 1967, Pat. No. y

3,529,054. 57 ABSTRACT [52] U S Cl 425/109 425/120 425/123 A rotatingfixture-mold for locating and holding type bearing 425/435 print membersin a spatical relationship to each other and to the axis of rotation ofthe fixture mold. The type bearing print 3 members when molded togetherform a drum structure which 18/DIG. 10; 264/261, 275, 596, 241, 245,260;

may be used as a printing drum or as an intermediate mold.

9 Claims, 18 Drawing Figures PATENTEDAPR 11 I972 3,655,309

SHEET 1 OF 3 IN Vlz'N'IUR.

NEAL HEPNER.

A T TORNEY PATENTEBAPR 11 I972 3,655,309

sum 3 BF 3 ooo ROTATING FIXTURE-MOLD FOR FABRICATING PRINTING DRUMS Thisis a division of application Ser. No. 690,041 filed Nov. 15, 1967 US.Pat. No. 3,529,054 issued Sept. 15, 1970 entitled Method for FabricatingPrinting Drums which is assigned to the same assignee.

FIELD OF THE INVENTION This invention relates generally to an apparatusfor use in fabricating structures of various geometric shapes having anaxis of rotation such as printing drums and wheels.

SUMMARY OF THE INVENTION A rotatable fixture mold having a cylindricalcavity along its axis of rotation. The ends of the cavity are defined bya pair of detachable end plates. The volume enclosed by the cylindricalwall of the cavity and the inside faces of the end plates define afixture chamber into which a plurality of type bearing print members areplaced. The type bearing print members are located by a plurality ofprojections placed on at least one surface within the cavity. Adjacentto one end plate and coupled thereto is an inlet chamber for receiving amoldable material which is to be placed within the fixture chamber. Inorder to transfer the moldable material from the inlet chamber to thefixture chamber there is at least one port extending through one endplate through which the molding material can transfer.

IN THE DRAWINGS FIG. 1 is a perspective view of apparatus which may beemployed to rotate the fixture-mold;

FIG. 2 is an end view of the fixture-mold partly broken away and insection;

FIG. 3 is a sectional view, taken along the line 3-3 of FIG.

FIG. 4 is a perspective view of a drum rim structure fabricated with theuse of the fixture-mold of FIGS. 2 and 3 and the apparatus of FIG. 1;

FIG. 5 is a perspective view of another fixture-mold to receive the rimstructure of FIG. 4;

FIG. 6 is a perspective view of the finished printing drum;

FIGS. 7 to 11 are fragmentary sectional views, illustrating the steps ofa method utilizing the fixture-mold;

FIG. 12 is an exploded perspective view of a fixture-mold of anotherembodiment;

FIG. 13 is a perspective view of a drum rim structure fabricated withthe use of the fixture-mold of FIG. 12;

FIG. 14 is a perspective view of another fixture-mold to receive the rimstructure of FIG. 13;

FIG. 15 is a perspective view of the completed printing drum;

FIGS. 16 and 17 are fragmentary sectional views illustrating certainsteps of a method utilizing the fixture-mold of FIG. 12; and

FIG. 18 is a perspective view of a rim structure element of the drum rimstructure of FIG. 5.

DETAILED DESCRIPTION Referring to the drawings by characters ofreference, and in particular to FIGS. 2, 3, 4, and 18, there isillustrated a fixturemold 101 for use in fabricating a plurality of rimsegments 103 into a drum rim structure 100. The mold 101 is of sectionalconstruction comprising a sleeve 105, defining a cylindrical wall,closure walls comprising a first end plate 107, and a second end plate109, and an end cap 113. The several sections of the mold 101 arefastened together by any suitable means such as screws and bolts whichare shown in FIG. 3. The two axially opposed end plates 107 and 109 andthe sleeve 105, when fastened together, define an annular moldingchamber surrounding a cylindrical fixture chamber or cavity, into whichthe rim segments 103 are placed and held. Each rim segment 103 has anelongated web 102 to which a rim forming head or flange 104 is attached.As is illustrated in FIG. 18, along the broad surface of the head 104there is securely located in a row a plurality of type faces orcharacters 106.

In the cylindrical fixture cavity, the rim segments 103 are located andheld between a plurality of spacers 115 which are integral with and onthe inner surface of the first end plate 107 and a plurality of axiallyopposed spacers 119 which are integral with and on the inner surface ofthe second end plate 109. Both sets of spacers 115 and 119 are equallyspaced in an angular relationship about the center of the plates 107 and109. The circumferential distance between adjacent spacers is slightlylarger than the thickness of the web 102 of the rim segment. Therefore,each segment is held by adjacent spacers so as to permit movement withinthe fixture in the radial direction only. The axial distance between thespacers 115 and 119 and the inner wall 114 of the sleeve or the annularmolding chamber defines the radial thickness of the drum rim cavity andis slightly greater than the thickness of the head 104 of the rimsegment 103.

In the second end plate 109, there is also a plurality of ports orapertures 111 equally spaced in an angular relationship about the centerof the plate 109. With respect to the spacers 119, the apertures 111 arelocated adjacent to each spacer and on the inside of each spacer. It isthrough these apertures 111 that the molding material 127 enters intothe cylindrical fixture cavity.

The end cap 113 provides an inlet cavity 123 to the mold 101. The cavityis conical in shape extending from the inlet 121 to the surface of thesecond end plate 109. The major diameter or flared end of the inletcavity 123 is equal to or greater than the diametric distance spanningtwo apertures 111; thereby each aperture 111 is wholly within theconical cavity.

With the second end plate 109 and the end cap 113 removed, the rimsegments 103 are loaded into the fixture cavity by slideably inserting aweb 102 between each spacer 115. The head portion 104 is positionedbetween the spacer and the inner wall 114 of the sleeve in the moldingchamber. The second end plate 109 is then positioned over the oppositeend of the rim segment 103 thereby securely holding each segment 103.The end cap 113 is then placed over the end plate forming the completedfixture-mold. This is illustrated in FIG. 7.

The mold 101 is rotated about its axis which may be accomplished bycoupling the mold to the axis of a motor as is illustrated in FIG. 1.When the mold is rotating, the centrifugal force which is generated,causes the rim segments 103 to move in a radially outward direction sothat the type faces 106 are in an abutting relationship with the innerwall or surface 114 of the sleeve. This is illustrated in FIG. 8.

During rotation, a predetermined amount of molding material 127 isintroduced into the molding chamber through the inlet' 121. The taperedsides of the inlet chamber 123 direct the material toward the apertures111. The material is placed in rotation in the chamber, and when thematerial reaches the apertures, it enters therethrough into the annularmolding cavity under rotation and does not splash against the rimsegments 103. With the apertures so positioned, the material is directedinto the annular cavity without touching the segments 103 in the areawhere the material is not to be molded. The reason for avoiding anycontact other than that desired, is to prevent contamination which maybe detrimental to any subsequent operations. The radial thickness of therim depends upon the amount of material 127 which is introduced into theinlet 121. This is illustrated in FIG. 9.

The purpose of the molding material in such a drum rim structure 100 asshown for example, in FIG. 4, is to provide a temporary holding fixturewhich holds the rim segments 103 together unaided and which also sealsthe encapsulated flange 104 of the rim segments during a subsequentmolding operation. Since the structure 100 is used as a temporaryholding fixture, one of the fusible alloys such as Cerrolow 117, analloy comprising Bismuth 44.7 percent, Lead 22.6 percent, Tin 8.3percent, Cadmium 5.3 percent and Indium 19.1 percent, as marketed byCerro de Pasco Sales Corporation can be used. Other materials could alsohave been used such as rubber, plaster, resin epoxy, phenolic, etc.,depending upon the ultimate use of the drum rim structure 100.

After the molding material has hardened, the mold 101 is disassembledand the unitary drum rim structure 100 is removed from within the sleeve105. Next the drum rim structure is placed within a second mold, asillustrated in FIG. 5 to complete the fabrication of a printing drum129, illustrated in FIG. 6.

The second mold, as shown in F IG. 5, comprises a pair of end caps 133and 135 which are placed over each end of the rim structure 100. Bothcaps 133 and 135 have a coaxial aperture 139 to locate and support amounting shaft 131. Also, the top end cap 133 has a plurality ofopenings 141 therein to allow a permanent molding compound to be pouredinto the inner chamber of the rim structure. The bottom end cap has noother openings other than the shaft location aperture. Both caps 133 and135 are coupled together through a series of bolts 137 placed outwardlyof the structure 100.

After the second mold is assembled, a permanent molding material 143 ispoured into the chamber. By way of illustration in the fabrication ofthe printing drum 129, the molding material 143 comprised: 28 parts byweight of Shell Epon Resin 815, an epichlorohydrin/ bisphenol A-typeepoxy resin having an average molecular weight of approximately 330 andan equivalent weight of about 185 as marketed by Shell Chemical Co, 12parts by weight of Genamid 250, a fatty amidoamine resin having an aminevalue of approximately 425, as marketed by General Mills, Co., which isthe hardener, and 60 parts by weight of Reynolds Aluminum No. 200 afiller comprising 98 percent pure Aluminum powder and 2 percentimpurities. This mixture provides a strong bond between the rim segments103 and the shaft 131 and with the aluminum filler, the shrinkage isreduced to an acceptable amount. This is illustrated in FIG. 10.

After the molding mixture 143 has cured the end caps 133 and 135 areremoved and the dissolvable molding material 127 is removed from theperiphery of the drum and the drum is complete as illustrated in FIG. 6.

Referring to FIGS. 12 through 17, there is shown and illustrated afixture-mold of another embodiment. The fixturemold 155, shown in FIG.12, is used to locate and hold a plurality of discs 149 in apredetermined spaced relationship for fabricating into a drum-likestructure 169, which is shown in FIG. 13. The discs 149 have a pluralityof type faces or characters 150 spaced around the periphery thereof.

The fixture-mold 155 is of sectional construction comprising a first endplate or closure wall 163, a sectional sleeve 159 and 161 which togetherform a cylindrical wall, a second end plate 165 or closure wall and anend cap 167. The several sections of the mold 155 are fastened togetherby any suitable means such as screws and bolts. The two end plates 163and 165 and the sectional sleeve 159 and 161 when fastened together,form a cylindrical fixture cavity or chamber and an annular moldingcavity or chamber within the fixture into which the several discs 149are placed and held.

In the cylindrical fixture cavity, each disc is located and held bythree projections 174, 175, and 176 which extend from the inner walls171 and 173 of the sleeve sections. These projections are angularlyspaced apart about the axis of the cavity with one projection 174located on the inner wall 173 of the sleeve section 161 at the apex ofthe section. The other two projections 175 and 176 extend from the innerwall 171 of the other sleeve section 159. In the present embodiment, theprojections 174, 175, and 176 are basically shaped in the form offrustum of a cone with an impression of a type character formed in theoutboard surface. The type face 150 on the disc 149 is located withinthe impression on each projection and securely held thereby. The axialdistance between projections corresponds to the center to centerdistance A of adjacent type along a row of type. The length of theprojections from the inner walls determines the amount of moldingmaterial 156 which will overlie and encapsulate the type faces 150.

With both end plates 163 and fastened to the sleeve section 159 whichhas two projections and 176 per disc, the desired number of discs areloaded by positioning the correct type face on each projection 175 and176 lying within a given circular plane of the cavity. After all thediscs are loaded, the other sleeve section 161 is positioned over thediscs and fastened between the two end plates 163 and 165.

The second end plate 165 has a plurality of ports or apertures 181equally spaced in an angular relationship about the center of the plate.The radial distance to the apertures 18] is such as to position themsubstantially above the type faces 150 of the discs 149. It is throughthese apertures that the molding material 156 enters into the annularmolding cavity.

The end cap 167 provides an inlet cavity to the mold 155. The cavity isdefined by an endless conical surface 177 extending from the inletaperture 179 to the surface of the second end plate 165. The diameter ofthe cavity at the end plate or flared end of the cavity is equal to orgreater than the diametn'c distance spanning two apertures 181; therebyeach aperture is wholly within the conical inlet cavity. The end cap 167is securely fastened over the second end plate 165 forming the completedfixture-mold 155 containing the discs therein.

The mold 155 is rotated about its axis which may be accomplished bycoupling the mold to the axis of a motor or any similar rotating shaft.

During rotation, a predetermined amount of molding material 156 isintroduced into the mold through the inlet 179. The tapered sides 177 ofthe inlet chamber direct the material toward the apertures 181. Thematerial 156 is placed in rotation in the chamber and when the materialreaches the apertures, it enters therethrough into the annular moldingcavity under rotation and does not splash against the discs 149. Withthe apertures 181 so positioned, the material is directed into theannular cavity without touching the discs in the fixture chamber wherethe material is not to be molded. The reason for avoiding contact withsurfaces that are not to be molded, is to prevent contamination whichmay be detrimental to any subsequent operations. The radial thickness157 of the rim depends upon the amount of material 156 which isintroduced into the inlet 179.

The purpose of the molding material 156 in such a drum structure 169, asshown for example in FIG. 13, is to provide a temporary holding fixturewhich holds the discs together unaided and which also seals theencapsulated type faces 150 of the discs during a subsequent moldingoperation. Since the structure 169 is used as a temporary holdingfixture, one of the fusible alloys, such as Cerrolow 117, an alloycomprising Bismuth 44.7 percent, Lead 226 percent, Tin 8.3 percent,Cadmium 5.3 percent and Indium 19.1 percent, as marketed by Cerror dePasco Sales Corporation can be used for the molding material. Othermaterial could also have been used such as rubber, plaster, resin epoxy,phenolic, etc., depending upon the ultimate use of the drum structure169.

After the molding material has hardened, the mold 155 is disassembledand the unitary drum structure 169 is removed. Next the drum structureis placed within a second mold, as illustrated in FIG. 14 to completethe fabrication of the printing drum 147 illustrated in FIG. 15.

The second mold, as shown in FIG. 14, comprises a pair of end caps 182and 183 which are placed over each end of the drum structure 169. Bothcaps 182 and 183 have a coaxial aperture 187 to locate and support amounting shaft 151. Also, the top end cap 182 has a plurality ofopenings 189 therein to allow a permanent molding compound 191 to bepoured into the inner chamber of the drum structure. The bottom end cap183 has no other openings other than the shaft location aperture. Bothcaps are coupled together through a series of bolts placed outwardly ofthe drum structure 169.

After the second mold is assembled, a permanent molding material 191 ispoured into the chamber. By way of illustration in the fabrication ofthe printing drum 147, the molding material 191 comprised: 28 parts byweight of Shell Epon Resin 815, an epichlorohydrin/ bisphenol A-typeepoxy resin having an average molecular weight of approximately 330 andan equivalent weight of about 185, as marketed by Shell Chemical Co., 12parts by weight of Genamid 250, a fatty amidoamine resin having an aminevalue of approximately 425, as marketed by General Mills, Co., which isthe hardener, and 60 parts by weight of Reynolds Aluminum No. 200 afiller comprising 98 percent pure Aluminum powder and 2 percentimpurities. This mixture provides a strong bond between the discs 149and the shaft 151 and with the aluminum filler, the shrinkage is reducedto an acceptable amount. This is illustrated in Fig. 16.

After the molding mixture 191 has cured the end caps 182 and 183 areremoved and the dissolvable molding material 156 is removed from theperiphery of the drum and the drum is complete as is illustrated in FIG.15.

lclaim:

l. A rotating fixture-mold for fabricating printing drums from aplurality of character-bearing print members comprismg:

a cylindrical wall open at each end,

closure walls closing each end of said cylindrical wall and cooperabletherewith defining a fixture chamber,

locating members on at least one of said walls, said members projectinginwardly into said fixture chamber and concentric therewith providingmeans to locate and align the plurality of character bearing printmembers within said fixture chamber, and

a cap cooperating with one of said closure walls to define an inletchamber, said one closure wall having a port therethrough to effectcommunication between said inlet chamber and said fixture chamber forthe introduction of a moldable material into the fixture chamber.

2. The rotating fixture-mold according to claim 1 wherein the locatingmembers are a plurality of angularly and axially spaced projections onthe cylindrical wall.

3. The rotating fixture-mold according to claim 2 wherein theprojections are in the form of a frustum of a cone extending inwardlyfrom the cylindrical wall a predetermined distance.

4. The rotating fixture-mold according to claim 3 wherein the outboardsurface of said projections has an impression of one of the type of theprint members to receive the corresponding type on the print member forsupporting the print memberthereby.

5. The rotating fixture-mold according to claim 1 wherein the locatingmembers are a plurality of axially opposed spacers equally and angularlyspaced on each of the closure walls for maintaining the print membersparallel to the axis of rotation of the fixture-mold.

6. A rotatable fixture-mold for fabricating drum rims comprising acylindrical sleeve, closure members closing the ends of said sleeve,elongated rim segments having a flanged portion thereon extending in thedirection of length of said segments, spacers on the inner faces of saidclosure members for holding said rim segments in angular spaced apartrelationship about the axis of said sleeve and said spacers cooperablewith said flanged portions for defining a fixture chamber and a moldingchamber surrounding the fixture chamber and a cap cooperating with oneof said closure members defining an inlet chamber, said one closuremember having ports therethrough adjacent to and inwardly of saidspacers for effecting communication between said molding chamber andsaid inlet chamber for the introduction of a moldable material into themolding chamber.

7. A rotatable fixture-mold according to claim 6 wherein said rimsegments have a T-shaped cross section extending in the direction oflength of said segments and flanged cross bar of said cross sectionbeing a separating member between said fixture chamber and saidsurrounding molding chamber.

8. A rotatable fixture-mold according to clarm 6 wherein the other ofsaid closure members has an aperture therein substantially the diameterof said fixture chamber for limiting the amount of moldable material insaid molding chamber thereby limiting the thickness of the drum rim.

9. A rotatable fixture-mold for molding a plurality of rim segments intoa drum rim structure, said fixture-mold comprising:

a cylindrical sleeve open at each end,

a first and second plate enclosing each end of said sleeve, each of saidplates cooperating with the inner surface of said sleeve forming anannular molding chamber therein,

a plurality of axially opposed alignment members equally and angularlyspaced on said plates extending inwardly of said annular moldingchamber, said members for aligning and supporting the rim segments,

an inlet chamber adjacent to said first plate and having a flarred endsubstantially equal in dimension to said annular molding chamber forreceiving and directing the molding material thereto, and

a plurality of equally and angular spaced apertures in said first plateinterconnecting the flarred end of said inlet chamber with the annularmolding chamber for transferring the molding material from said inletchamber to said annular molding chamber.

1. A rotating fixture-mold for fabricating printing drums from aplurality of character-bearing print members comprising: a cylindricalwall open at each end, closure walls closing each end of saidcylindrical wall and cooperable therewith defining a fixture chamber,locating members on at least one of said walls, said members projectinginwardly into said fixture chamber and concentric therewith providingmeans to locate and align the plurality of character bearing printmembers within said fixture chamber, and a cap cooperating with one ofsaid closure walls to define an inlet chamber, said one closure wallhaving a port therethrough to effect communication between said inletchamber and said fixture chamber for the introduction of a moldablematerial into the fixture chamber.
 2. The rotating fixture-moldaccording to claim 1 wherein the locating members are a plurality ofangularly and axially spaced projections on the cylindrical wall.
 3. Therotating fixture-mold according to claim 2 wherein the projections arein the form of a frustum of a cone extending inwardly from thecylindrical wall a predetermined distance.
 4. The rotating fixture-moldaccording to claim 3 wherein the outboard surface of said projectionshas an impression of one of the type of the print members to receive thecorresponding type on the print member for supporting the print memberthereby.
 5. The rotating fixture-mold according to claim 1 wherein thelocating members are a plurality of axially opposed spacers equally andangularly spaced on each of the closure walls for maintaining the printmembers parallel to the axis of rotation of the fixture-mold.
 6. Arotatable fixture-mold for fabricating drum rims comprising acylindrical sleeve, closure members closing the ends of said sleeve,elongated rim segments having a flanged portion thereon extending in thedirection of length of said segments, spacers on the inner faces of saidclosure members for holding said rim segments in angular spaced apartrelationship about the axis of said sleeve and said spacers cooperablewith said flanged portions for defining a fixture chamber and a moldingchamber surrounding the fixture chamber and a cap cooperating with oneof said closure members defining an inlet chamber, said one closuremember having ports therethrough adjacent to and inwardly of saidspacers for effecting communication between said molding chamber andsaid inlet chamber for the introduction of a moldable material into themolding chamber.
 7. A rotatable fixture-mold according to claim 6wherein said rim segments have a T-shaped cross section extending in thedirection of length of said segments and flanged cross bar of said crosssection being a separating member between said fixture chamber and saidsurrounding molding chamber.
 8. A rotatable fixture-mold according toclaim 6 wherein the other of said closure members has an aperturetherein substantially the diameter of said fixture chamber for limitingthe amount of moldable material in said molding chamber thereby limitingthe thickness of the drum rim.
 9. A rotatable fixture-mold for molding aplurality of rim segments into a drum rim structure, said fixture-moldcomprising: a cylindrical sleeve open at each end, a first and secondplate enclosing each end of said sleeve, each of said plates cooperatingwith the inner surface of said sleeve forming an annular molding chambertherein, a plurality of axially opposed alignment members equally andangularly spaced on said plates extending inwardly of said annularmolding chamber, said members for aligning and supporting the rimsegments, an inlet chamber adjacent to said first plate and having aflarred end substantially equal in dimension to said annular moldingchamber for receiving and directing the molding material thereto, and aplurality of equally and angular spaced apertures in said first plateinterconnecting the flarred end of said inlet chamber with the annularmolding chamber for transferring the molding material from said inletchamber to said annular molding chamber.